Prism



88. UlllUb QUal bll Huuu June 29, 1937. 0. K. KASPEREIT 2,085,026

PRISM Filed Nov. 14, 1955 T 2 5 37 i Y 9 Inventor Elttm K KaspareitAttorney Patented June 29, 1937 UNITED STATES PATENT OFFICE 1 Claim.

(Granted under the act of March 3, 1883, as

amended April 30, 1928; 370 0. G. 757) The invention described hereinmay be manufactured and used by or for the Government for governmentalpurposes, without the payment to me of any royalty thereon.

The subject of this invention is a prism designed primarily to deviatethe line of sight through an angle of 90 in the horizontal plane andthrough an angle of 45 in the vertical plane and neither invert norrevert the image.

The prism is so designed as to be constructed of one piece of glass.

A practical embodiment of the invention is illustrated in theaccompanying drawing, wherein:

Fig. 1 is a plan view.

Fig. 2 a side elevation, and

Fig. 3 an end elevation.

Referring to the drawing by characters of reference:

The prism is so formed that the angle alpha is equal to 22 30, the anglebeta is equal to 45, the angle gamma is equal to 90 and the angle deltais equal to 112 30.

There is provided an entrant face I of quadrangular formation, oppositewhich is the reflecting face 2 making an angle of 45 with the face I. Anupper inclined face 3 makes an angle of 45 with the face 2, while a face4 parallel to the face I, and inclined end face 5 making an angle of 90with the top face 3 and the faces 6 and 1, making an angle of 90 witheach other and angles of 45 with the sides I and 4 respectively completethe prism.

From the foregoing it will be evident that the rays a, b and c which arerays emanating from points transverse of an object will enter the prismat the face I and be reflected at right angles from the face 2 toimpinge upon the face 3 when they are again reflected at right angles,some to the face 6 and others to the face I, when those impinging uponthe face 6 are reflected at 5 right angles to the face I, and thoseimpinging upon the face 1 are reflected at right angles to the face 6and from each of these faces the rays so reflected are again reflectedto pass through the face 3 to the eye of the observer. 10

The rays a, d and e in the vertical plane pass through the face I andimpinge upon the face 2, at which face they are reflected at rightangles to the face 3. From the face 3 the rays are reflected at rightangles to the faces 6 and l or the juncture of such faces and are thenreflected at an angle of 45 through the face 3 to the eye of anobserver.

I claim:

A prism embodying an entrant face, a reflecting face disposed at anangle of 45 to the entrant face, a second reflecting face disposed at anangle of 45 to the path of the rays of light reflected from the firstreflecting face, the plane of the second reflecting face forming anangle of 45 with the plane of the first reflecting face, reflectingfaces disposed at an angle of 90 to each other and forming a roof tointercept the rays reflected from the second reflecting face andinter-reflect the same to revert the image back to normal and reflectthem through the emergent portion of the second reflecting face, theridge of the roof extended forming with the central longitudinal axis ofthe second reflecting face extended an angle of 22 30'.

O'I'I'O K. KASPEREIT.

